Possible to lock data validation and yet permit cell editing?

What I'm trying to achieve is to be able to lock the text length of a column so that users can enter text data into that column but not exceed the allowable length for our purposes. I've found a way to use auto loading macros to make a popup if they exceed the set length. However, that is useless for our purposes because 1) pasting data into the cells as opposed to manually entering data overrides the validation just as it does when you set it with the data validation menus, 2) it requires that macros be activated in the end user's computer which we cannot guarantee will happen. If you lock in the data validation by protecting the worksheet, the end user can't enter data. Do you know of a way to lock in the data validation without using active controls like macros, and yet allow the end user to enter data into the cells. (Perhaps a solution would be to somehow prevent the pasting of data into a cell forcing the data validation to be utilized?) Thanks in advance for any insight or advice you might have.